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(No Model.)

R. au F. G'ARRBTT.

TUBULAR BOILER AND'PURNAGB.

Patented JuneO, 1882.

UNITED STATES PATENT FFICR.

RICHARD .GARRRTI AND 'FRANK GARRETT, on LEIsToN WORKS, [LEI'sroN,

, COUNTY on sUFFOLK, ENGLAND.

TUBULAR BOILER AND FURNACE.

SPECIFICATION forming part of Letters 'Patent No. 259,845, dated June20, 1882.

Application filed J une 13, 1881.

(No model.) Patented in England March 11, 1881. No. 1,060; in FranceJuly 7, 1881, No. 143,840; in

Germany July B, 188i, No. 16,701; in Austria July 9, 1881, No. 16,890;in Belgium July 2l, 1881, No. 55,222,` and in Ital-y July 25,

.To all whom it may concern:

Be it known that we, RICHARD GARRETT and FRANK GARRETT, both of LeistonWorks, Leiston, in the county of Suffolk, England, have invented certainImprovements in the Construction of Tubular Boilers and Furnaces, ofwhich the following is a specification.

The chief object ofthisiuvention is to effect an economy in theconsumption ofthe fuel burned in the furnaces of tubular steam-boilers,and also the prevention of smoke and the arrest of sparks and solidsarising from the burning fuel-as, for instance, thc silicious depositV.emanating from burning straw.

The invention relates to portable and locomotive-engine boilers, thenre-tubes of which lie horizontaland lead directly from thecombustion-chamber to the smoke-box.

In applying ourv invention to portable orlocomotive boilers we cut offfrom the furnace the combustion-cham ber by extending the bridge, orascreen which serves the purpose of abridge, to a height approaching nearto the crown of the furnace, and extending through the boiler at aslightly-lower level than the crown of the furnace is a row ofair-tubes,which reach from the tube-plate of the combustion-chamber toand through the smoke-box. The outer ends of these tubes are open to theatmosphere, and they serve to draw .in air and convey it in a heatedstate to the combustion-chamber for the purpose just explained.

In the accompanying drawings, Figure lis' a longitudinal section of theboiler and furnace of a portable engine with our improvements adaptedthereto. Fig. 2 is a cross section takenintheline l2 of Fig. l orthrough thefur nace. Fig. 3 is a partial sectional plan of the furnace,and Fig. 4 is an elevation of the smoke-box end of the boiler.

In these figures, A is the furnace, B is the bridge,and C thecombustion-chauiber.

D D are the fire-tubes leading from the combustion chamber through thebarrel of the boilerzand ending in the tube-plate of the smoke-box E.

The bridge B is composed of two verticallyhinged doors, which are madeof frames of iron faced with fire-brick. These doors are capable ofheilig swung back, as indicated by dots in Fig. 3, to expose the ends ofthe fire-tubes for cleaning and repairs. The bridge B, it willbe seen,rises near to the crown ofthe furnace and near the level of the top rowof lire-tubes. These tubes (marked D) we now propose to convert intoair-tubes by inserting into their forward ends short tubes F F, whichextend to thefront of the smoke-box and are made fast to the endv platethereof. These tubes F are open tothe atmosphere, and their inner endsare drawn down, so as to enable them tofittightly in the tubes D.Air-passages are thus estab lished between the smoke-box end oftheboiler and the combustion-chamber, and when thefire.

is burning and a sufficient draft is established in the fire-chamber airwill be drawn in through these tubes, heated by the gases in thesmokeboX, and supplied to the combustion-chamber. In front of the outerends of these tubes are hung small swing regulating doors or gatesf,which, when dropped into place, as best shown in the enlarged views,Fig. 5, will close the tubes and prevent smoke escaping therefrom whenthe furnace-tireis first ignited. So soon,

however, as the furnace becomes hot, these doors f are to be raisedsufficiently to admitan adequate supply of air, which will pass into andthrough the tubes F to thc combustionchamber.

' We prefer to connect the steam and water space above the crown of thefurnace, by a pipe, H, in the vertical plane of the bridge, with thewater space or jacket below the ashpit. This is for the purpose ofkeeping up a good circulation of water in the front part of the boiler;but the tube also serves as a stay for the crown of 'the furnace and asan abutting piece for the hinged doors which form the raised bridge B.

The smoke-box is surrounded by a water- Y jacket, I I, through the upperpart of which vided, and the gases of combustion, being robbedof much oftheir heat by the surround ing water and by the air-tubes F, are causedto leave the boiler ata comparatively-low temperature.

This arrangement of boiler and furnace is intended especially forburning light fuelsuch as straw and stubblewhich require for theireficient consumption not merely the use of a eolnbustionfch'amber, (thetransverse wall Y or partition forming which serves to deflect the bysimply removing the small tubes F and closing the openings made for themin the end ofthesmokebox by the means above described.

As a modification of the means employed for delivering heated air-to thecombustionehamber, we propose in some cases to adopt the arrangementsshown in the sectional view, Fig. 6, where the row-ot' tire-tubes D haveinserted in them air-tubes F, which extend from the tube plate of thecombustion chamber through the fire-tubes and through the smokebox.These tubes will be open at both ends and will be held centrally orotherwise in their containing tubes by feathers or their equivalent.

We are aware that itis old to introduce air into the combustion-chamberof a steam-boiler to produce a more perfect combustion; and we are alsoaware that air has been introduced into the fire-tubes of a boiler bymeans of an injector or series of steam-jets. Hence we do not claim theabove as of our invention.

What we do claim as our invention, and desire to secure by LettersPatent, is-

1. The combination, with the raised bridge B and the tubes D', situatedat or immediately above the level of the bridge and extending from thecombustion-chamber to the smokebox, of the tubes F, extending throughthe smoke-box and enteringthetubes D', whereby the combustion-chamber isbrought into com-V munication with the open air and streams of heatedair are caused to meet and mingle with the gases of combustion as theyrise over the bridge to reach the combustion-chamber, substantially asspecitied.

2. The raised bridge B, constructed of abutting doors, which are hingedvertically 011 opposite sides of the furnace, and which afford, on beingthrown back, ready access to the .flue-tubes forcleaning and repair,substantially as specified.

3. The combination, with the furnace having the circulating-pipe H,extending from top to bottom thereof,ot'the bridge-wall B, composed oftwo doors hinged vertically at the opposite sides ofthe furnace andclosing against said pipe, substantially as specified.

RICHARD GARRETT. A FRANK GARRETT. Witnesses to the signature ofthe saidRichard Garrett: Y

RoB'r. C. MAY,

6 Great George St., Westminster. THos. PHILLIPS,

35 Walbrook, London, E. O. Witnesses to the signature of the said FrankGarrett:

H. K. WHITE, GEO. GAN'rLF.,

Both 0f 66 Chancery Laue, London.

